This quote gives us important information: firstly, it testifies that the use of the concerto grosso and concertino (tutti and solos) was already established in Bologna in 1687. Then Perti claims that this was the common practice used in Rome and this assertion confirms Georg Muffat's witness in the preface to his Auserlesene mit Ernst und Lust gemengte Instrumental-Musik (Passau, 1701). Muffat writes that “some time ago I heard with great excitement and amazement some concertos of the talented Archangelo Corelli performed most beautifully and with great precision by a large number of instrumentalists”14. He is referring to the journey to Italy that he took in 1681-1682 in order to learn the Italian musical style with Bernardo Pasquini in Rome. Perti's letter gives us an evidence that this was a common performance practice in Rome already 27 years before the publication of Corelli's op. 6.

Fig. 10 Cristoforo Schor, Veduta della piazza con la festa, 168715

But, more precisely, Perti is referring to the use of concerto grosso and concertino as an orchestral instrumentation for the oratorio. He alludes, therefore, to an even earlier praxis, which has been, in fact, established in Rome by Alessandro Stradella. Stradella was the first composer to introduce the concept of concerto grosso: the first composition that shows the use of this technique is the serenata "Vola, vola in altri petti" (Rome, 1674). He also used it for purely instrumental music (Sonata di viole, Sonata a otto viole con una tromba in D major) and in oratorios (the best example can be found in his San Giovanni Battista”Rome1675).

The concerto grosso is nothing other than an instrumental transposition of the alternation between soloists and choir, widely adopted in the tradition of the polychoral polyphony, into a purely instrumental context. But thanks to Stradella it became an independent fact from the vocal and choral structuring of a composition, as an autonomous instrumental construct. In Stradella's compositions we can find already all the elements that will be paradigmatic for the concerto grosso amongst his successors: the alternation between soloists and tutti is not simply used as an antithesis of different dynamic levels, but it has a thoughtful individuality.

Let us now investigate which forms have been adopted, for the use of the concerto grosso 'orchestration' in purely instrumental music. In the Roman environment, the genre used is the one of the Baroque Sonata, in its twofold conjugation: da chiesa and da camera. Consisting of four movements, usually alternated between slow and fast. The concertos written in the da camera style present movements set on the structures of the most common dances used for instrumental compositions, such as Allemanda, Corrente, Gavotta, Sarabanda, Giga. The ones written in the da chiesa style cannot be exempted from having the typical fugue, or fugato motif, for the second movement, while the other movements are most of the time dance-inspired compositions. Arcangelo Corelli's op. 6 represents probably the highest finest example of this practice, followed by the musical production of those musicians that belonged to his 'school' (e.g., Muffat, Handel, Geminiani).

Certain old-school musicology currents, Arnold Schering e.g., tended to divide the concerto grosso from the soloistic concerto into separate chapters in the history of music. I do not think it is necessary to do that; for three reasons: the “grosso” part (tutti) is present in both cases; the role of the concertino/solo consists in both scenarios of a function of integration or contrast against the proposal of the tutti, and as we just saw above, such a function is ingrained in the concept of concerto itself; they both coexisted for at least two decades without a formal distinction. My purpose in this chapter is to show what has been the evolution of this form, as an orchestral musical genre, from its origins, thanks to the Roman school, to the concept that still stands nowadays, elaborated in the Bolognese environment and, particularly, by Torelli.

Let us first examine what has been the background that allowed the Bolognese masters to take over this genre and transform it in what we all know. A first clue in my reconstruction is given by Giacomo Antonio Perti in a letter that he wrote to the Modena Court Secretary Giovanni Battista Giardini on the 10th of March 1687, while he explains how the Oratorio in San Petronio in Bologna is performed:

l'Oratorio è a 6 voci, con concertino, e concerto grosso all'usanza di Roma, ed anche vi è obbligata la tromba […] vi è necessaria quantità di strumenti

[the Oratorio has to be written for 6 voices, with a Concertino and a Concerto Grosso, as it is habit in Rome, and an obbligato part for the Trumpet […] a great number of instrumentalists is necessary].13

The Concerto in the Roman school

Fig. 9 Author unknown, Portrait of G. A. Perti, XVIII century, Bologna, Museo internazionale e biblioteca della musica.